Alex Hornstein thinks small about a challenge that vexes roughly one-fifth of the world’s population: how to power your home if you live somewhere without access to electricity.

That somewhere includes Alibijaban, a Philippine island that sits eight minutes from the mainland by boat. The outpost’s roughly 300 households buy car batteries to power lights, charge phones, and run TVs, DVD players, and fans. Each week, residents carry or courier their batteries to San Andres, a town on the mainland with electricity, where they recharge them at a hardware store or welding shop.

Hornstein saw the setup firsthand during his residence a few years ago in Manila, where he and fellow inventor Shawn Frayne developed the Solar Pocket Factory, a coffee table-size machine that makes panels small enough to power pocket-size devices.

Alibijaban’s remoteness suggested a solution. "It led to this idea we call Tiny Pipes, which is making solar panels that are controllable over a cellular network," says Hornstein, a 28-year-old MIT-trained engineer who since has relocated to Shenzhen, China. In early October, Hornstein, with the blessing of the Philippine utility Quezelco, began a trial that involves installing a 60-watt solar panel on the roofs of about 20 of Alibijaban’s homes. Hornstein has kitted out each of the panels with a card that connects to the cellular network. The unit represents what Hornstein calls "solar plus," which he describes as "embedding smart things into panels."

With the panel on its roof, a household can draw power to its battery, which stores the charge. Customers rent the panel from Tiny Pipes and pay for the power they use. "People can pay us through a phone, and we unlock the panel for 24 hours or they set up a daily or weekly or monthly plan," Hornstein says.

The deal stands to be a bargain for Alibijabans, who consume the energy equivalent of about one U.S. cent a day. Residents currently pay anywhere from $1.50 to $2 a week to charge batteries, in addition to incurring the expense and hassle of hauling them back and forth to the mainland. "The aim is to find an elegant way to produce energy for people who are using little energy," says Hornstein.

Provided the panels can withstand typhoons—two of which of have struck the island since testing began, without dislodging the panels—Hornstein expects to expand Tiny Pipes to another 200 homes on Alibijaban and, starting in July, to 1,000 homes in Bacolod, a city of roughly a half million people in the country’s Negros Occidental province.

The pilot holds promise for the Philippines, where about 30 million people live off the grid and storm-prone provinces have proved difficult to electrify. The trial also holds hope for the roughly 1.5 billion people worldwide who cannot connect to the grid directly. "I want to be able to deploy Tiny Pipes at a scale that makes a dent," says Hornstein. "I'll start feeling like we're reaching that scale when we've hit a million installed panels."

"My ambition here is to make the largest, most widespread power grid in the world," he adds.

Tiny Pipes isn't the only company working on mobile-enabled rental of solar power. Simpa Networks, a Bangalore-based startup, delivers electricity via cellular-connected solar panels that households can purchase over time via a series of small payments. Other startups install panels that users can unlock with a mobile phone that uses Bluetooth technology. The firms each design their own circuitry, according to Hornstein, who notes that solar panel makers have yet to produce wirelessly controlled panels en masse.

Hornstein knows something about producing panels. He and Frayne raised nearly $78,000 last year via Kickstarter for Solar Pocket Factory, which landed them in the business of marketing a machine that could produce panels inexpensively nearly anywhere on the planet.

Eventually the duo decided the value lies not in making a machine that makes panels but in making panels themselves smarter. "One of the things we discussed was whether there was something we could add to the panel to make it more than a dumb device that sat in the sun and produced electricity?" says Hornstein, who sources panels for Tiny Pipes from a factory in Dongguan, China.

For Hornstein, success has two dimensions. One is "feeling like you’re lit up, when there’s nothing else you would rather be doing or should be doing than what you’re doing right now," he says. "The other side is how many lives you can impact."

I'm excited to finally hear about Hornstein and Frayne are up to these days. I was a backer of their Solar Pocket Factory but I always knew they would be on to something bigger.

In addition to Tiny Pipes and Simpa Networks, there are plenty of other companies who deliver clean and affordable solar energy with mobile money payments to the developing world. They include Angaza Design, M-KOPA, Azuri, and others. I suggest everyone who's interested in helping companies like these grow and scale their operations to check out SunFunder (http://www.sunfunder.com). On our platform, anyone can invest in off-grid solar projects implemented by similar companies. You get repaid in about a year, and people like Hornstein and Frayne can continue making the world a better place one solar panel at a time.